Automatic gear-changing apparatus for road, rail or other vehicles



Sept. 1, 1959 w. D. *SUTHERLAND 2,901,915

AUTOMATIC GEAR-CHANGING APPARATUS FOR ROAD. RAIL OR OTHER VEHICLES 2 Sheets-Sheet 1 Filed Nov. 20, 1956 S T GT NE NE w mm a NA AM MM 5 0 o. Y DR R A ET T L YC RC E AE AP- R L L EL E GE E D N s N W S E R D E E] .P S MU mm R A 10 G afl N .....Z... Om m- A Y NW \fi 2 Y J n DD n a c H t: I l? S p 1, 1959 w. D. SUTHERLAND ,915

AUTOMATIC GEAR-CHANGING APPARATUS FOR ROAD. RAIL OR OTHER VEHICLES Filed Nov. 20, 1956 2 Sheets-Sheet 2 50. dfw emw Patented Sept. 1, 1959 AUTOMATIC GEAR-CHANGING APPARATUS FOR ROAD, RAIL OR OTHER VEHICLES William Drummond Sutherland, Isleworth, England, assign'or to C.A.V. Limited, London, England Application November 20, 1956, Serial No. 623,407

2 Claims. (Cl. 74-336) This invention relates to electrically operated automatic gear-changing apparatus for road, rail, or other vehicles, of the kind in which the control is effected at least in part by a means which is responsive to the speed of the vehicle.

In some forms of apparatus of the kind aforesaid, there exists the undesirable possibility that in the event of failure of the speed responsive device while the vehicle is running at a normal speed, the gear changing mechanism will automatically revert to the low speed condition, and the object of the present invention is to enable this result to be automatically prevented.

A gear-changing apparatus of the said kind in accordance with this invention has combined with it an emergency device adapted to render the gear-changing apparatus ineffective in the event of failure of the speed responsive device.

In the accompanying drawings, Figures 1, 2, and 3 respectively illustrate three typical embodiments of the invention as applied to an apparatus for a 4-speed gear box.

Referring to Figure 1, the apparatus there shown comprises a plurality of electromagnets 1, 2, 3, 4, for effecting the gear changes, corresponding electromagneticallyoperated contactors to be hereinafter specified for controlling the supply of current to the said electromagnets from a battery or other substantially constant-voltage source, and speed-responsive relays actuated by current from a variable-speed direct current dynamo adapted to be driven by the vehicle for controlling the contactors, the armature of the dynamo being indicated by a and the field winding by b.

The electromagnets of the relays are represented by g, h, 1', these being connected to the dynamo and serving to close (at dilferent speeds of the dynamo) the associated contacts g h and P. In series with the contacts g is arranged the electromagnet d of a contactor which controls the normal closed contacts d in series with the gear-changing electromagnet 1, and the normally open contacts (I in series with the gear-changing electromagnet 2. In series with the contacts I1 is arranged the electromagnet e of the contactor which controls the normally closed contacts e s in series with the electromagnets 1, 2, respectively, and the normally open contacts e in series with the electromagnet 3. In series with the contacts i is arranged the electromagnet of the contact which controls the normally closed contacts f f respectively in series with the electromagnets 1, 2 and 3, and the normally open contacts f in series with the electromagnet 4.

The apparatus above described is already known, and is adapted to efiect the required gear changes through the electromagnets 1, 2, 3, 4 at difierent speeds of the dynamo.

In applying the present invention to the apparatus shown in Figure 1, there is provided an emergency contactor which is energised from the same source c as the others above described. This contactor comprises a delayed-action electromagnet k having in series with its 2 winding a pair of normally open switches e, F, these being arranged in parallel with each other, and respectively closable by the electromagnets e and j which control the third and fourth speed gears.

In parallel with the electromagnet k of the emergency contactor is arranged an associated contactor which comprises an electromagnet m arranged to control the normally closed contacts m and normally open contacts m and having in series with it a pair of contacts d k of which d are normally closed and movable to their open condition by the electromagnet d, and the others k being normally open and movable to their closed position by the electromagnet k of the emergency contactor. Further there is provided in parallel with these contacts the normally open contacts In which when closed by the associated electromagnet m serve to hold this electromagnet in action.

The arrangement is such that when either of the gear changing electromagnets 3 or 4 is in operation the corresponding contacts e or f are closed, so causing the electromagnet k to be energised and the contacts k to be closed. This however, has no eifect so long as the apparatus is working normally since the contacts d are held open by the electromagnet d. But in the event of failure of the speed responsive device, the electromagnet d will allow the previously open contacts d to reclose, and due to the contacts k being held temporarily closed by the delayed action of electromagnet k current will pass momentarily through the electromagnet m and efifect opening of the contacts m so isolating the gear-changing electromagnets 1, 2, 3, 4 from their source of energising current and closing the contacts m for keeping the electromagnet m in action. Thereupon all the gearchanging electromagnets will cause the associated gearchanging mechanisms to be moved into their neutral positions. Meanwhile the contacts k actuated by the electromagnet k of the emergency contactor will open after a short time delay, but the associated electromagnet in will remain operative, as the switch m in parallel with the contacts d and k will have been closed.

The system is also provided with additional switches n n under the control of the driver for isolating the apparatus from the current source and bringing the first gear into operation respectively.

The modified system illustrated by Figure 2 is essentially similar to that of Figure 1, but differs in that a transient current transformer p is provided in the position shown. The primary winding of the transformer is connected in series with the dynamo, and the secondary winding is connected in series with the winding 0 of a sensitive electromagnetic relay which controls normally open contacts 0 and normally closed contacts 0 Also the relay includes a hold-on winding 0 the latter being connected in series with the contacts 0 and the battery 0. In the event of failure of the speed responsive means, the sudden cessation of current through the primary winding of p results in a transient current in the secondary winding which passes through the relay winding 0 causing the contacts 0 to close and the contacts 0 to open for isolating the gear-changing electromagnets from the battery. The closing of the contacts 0 also brings the winding 0 into action for holding the contacts 0 open.

In the arrangement shown in Figure 3 the direct current dynamo of Figure 1 is substituted by an alternating current generator and an associated rectifier. Also in the speed responsive system is included an additional electromagnet q which controls normally open contacts q in series with the delayed action electromagnet k. The latter controls normally open contacts k in series with normally closed contacts d and the electromagnet m. The mode of operation is essentially the same as that of the arrangement shown in Figure 1. In the event of failure of the speed responsive system, the contacts d (having been opened by the electromagnet d) reclose and due to the delay action of k contacts k remain closed sufficiently long to allow the electromagnet m to isolate the gear-changing electromagnets 1, 2, 3, 4 from the current source 0.

The invention is not, however, restricted to the examples above described, as the details of the emergency means may be varied, provided always that it can prevent gear-changing to be efiected in the downward direction in the event of failure of the speed responsive means when the vehicle is travelling at a normal speed.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electrical system for the automatic control of a gear-changing apparatus employed in a road, rail or other vehicle, comprising in combination a source of electrical energy, means responsive to the speed of the vehicle, electromagnets for efiecting the gear-changing operations, circuital means connected to said source and electromagnets, switches forming parts of said circuital means and sequentially controllable by the speed-responsive means for enabling said electromagnets to be independently energised by said source, a normally-closed switch forming another part of said circuital means and situated between the first mentioned switches and said source, and emergency means controllable by said speed-responsive means for opening said normally-closed switch to render said electromagnets ineffective in the event of failure of said speed-responsive means.

2. An electrical system according to claim 1, in which said speed-responsive means includes a variable speed electric current generator, relays connected to and sequentially energisable by current from said generator, and contactors operable by said relays for controlling the first mentioned switches, and in which said emergency means includes an additional electromagnet for opening said normally closed switch.

References Cited in the file of this patent UNITED STATES PATENTS 20 2,615,349 Winther Oct. 28, 1952 2,647,411 Filocamo Aug. 4, 1953 2,714,435 DOzouville Aug. 2, 1955 

